1. Field
Example embodiments relate to a maskless exposure apparatus to perform an exposure operation without using a mask and without generation of stitching stripes and a stitching exposure method using the same.
2. Description of the Related Art
Generally, in a method of forming a pattern on a substrate of, for example, a Liquid Crystal Display (LCD), Plasma Display Panel (PDP), or Flat Panel Display (FPD), a pattern material is first applied to the substrate and then, is selectively exposed using a photo-mask such that a part of the pattern material, chemical characteristics of which have been changed, or the remaining pattern part is selectively removed, thus completing formation of a pattern.
However, as the size of a substrate is gradually increasing and the pattern precision is rising, costs related to a photo-mask increase substantially. Therefore, a maskless exposure apparatus to form a pattern on a substrate without using a photo-mask has been developed. The maskless exposure apparatus forms a pattern by transferring an exposure beam to a substrate (for example, a glass) based on pattern information that is generated using control signals by a Spatial Light Modulator (SLM), for example, a Digital Micro-mirror Device (DMD).
In the above described maskless exposure apparatus, an exposure head is aligned by an inclination θ with respect to a scan direction (Y-axis direction), to from a beam spot array tilted from an exposure plane. The on/off state of the beam spot array is under the control of the SLM while a stage is scanned in a main-scan direction, allowing a desired pattern to be transferred to the exposure plane. This maskless exposure is performed while the stage is driven in the scan direction (Y-axis direction), and an exposure area is enlarged or reduced via operation of an optical system.
However, in the maskless exposure, the SLM used to modulate an exposure beam according to the pattern has a small size and therefore, an exposure width in a sub-scan direction (X-axis direction) covered by a single exposure head is generally about 60˜70 mm even if the beam spot array is enlarged while passing through the optical system. Accordingly, in the case of a large substrate (for example, a glass having a size of 2 m or more), if an insufficient number of exposure heads cover the entire substrate, it may be necessary to perform exposure via appropriate stepping in the sub-scan direction (X-axis direction). Therefore, due to the stepping or even if the number of exposure heads is sufficient, there may exist a stitching area where exposure areas of the adjacent exposure heads overlap one another. The stitching area may cause stitching stripes according to an exposure dose.